A user device sometimes includes a subscriber identity module (SIM) card linked to a user account associated with the user device. The SIM card may include information to authorize a user device to access a network, such as a home cellular network or a roaming cellular network, via the user device. The SIM card may be interchangeable with multiple user devices so that one user account may be used to access the network using the SIM card. For example, a user may remove the SIM card from a user device, and install the SIM card in another user device to access the network using the other user device and the SIM card. While removing a SIM card from one device to another device may permit a level of convenience when a user replaces a user device, stolen or unauthorized user devices may be used to access the network when a user installs a SIM card in the stolen or unauthorized user device.